General Information

Event name: NZ-93-002
Nature of the harmful event:
Mass mortalities
Event directly affected:
Natural Fish
Toxicity detected: No
Associated syndrome:
Unexplained toxicity:
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: No
Event occurred before in this location: No
Individuals to contact: RHODES Lesley

Location & Date

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Location: Latitude: -41.285556, Longitude: 174.779167
General location information: Frank Kitts Park Lagoon, Wellington Harbour, North Island
HAB Area code(s): NZ-06
Additional location information:
Bloom event dates (yyyy/mm/dd): Event Date:1993-12-10
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information:


Causative organism known: Yes
Causative Species/Genus: Tetraselmis sp. (1 987 700 cells/L)
The fish deaths are attributed to anoxia brought about by a combination of reduced dissolved oxygen levels and the microalgae sticking to and clogging the secondary gill lamellae of the fish.
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information: Low numbers of the ichthyotoxic species Amphidinium carterae (Dinophyceae) and Heterosigma akashiwo (Raphidophyceae) were also present
Event-related bibliography: J. Brian Jones & Lesley L. Rhodes (1994) Suffocation of pilchards (Sardinops sagax) by a green microalgal bloom in Wellington Harbour, New Zealand, New Zealand Journal of Marine and Freshwater Research, 28:4, 379-383, DOI: 10.1080/00288330.1994.9516627

Environmental Conditions

Weather: Turbidity (NTU): Wind direction:
Stratified water: Oxygen content (nL/L): 0.002 Wind velocity:
Temperature (°C): Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: Current Velocity:
Nutrient information:
Temperature Range During Event: Max: 15.8 °C, Min: 15 °C
Salinity Range During Event:
Bloom location in the water column:
Growth Comments
Additional Environmental information:

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Kit used: Type of kit used:
Additional information:
Economic losses:
Management decision:
Additional harmful effect information: The involvement of an algal ichthyotoxin in the mortality cannot be completely dismissed due to the presence of the ichthyotoxic dinoflagellate Amphidinium carterae, although this species was present in very low numbers.
Created at 11:35 on 21 Jan 2018
Updated at 11:25 on 13 Mar 2018